Holographic sensors and their production

a technology of holographic sensors and production lines, applied in the direction of material testing goods, biochemistry apparatuses and processes, chemical methods analysis, etc., can solve the problems of limited application of gelatin to chemical sensing, unsuitable holographic film materials, and limited application of gelatin to holographic film materials

Inactive Publication Date: 2004-02-10
SMART HOLOGRAMS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

To date, however, few suitable holographic film materials exist.
The materials from which they are made and their structures render them unsuitable for sensing applications.
Applications of gelatin to chemical sensing are severely restricted by its complex chemical nature and hence the difficulty of chemically derivatising it in a rational way in order to change its analyte selectivity.
PVA-based holograms have some advantages over gelatin, but they are still very restricted in their scope, due to the incompatibility between the sensitive silver halide colloidal particles and the conditions required to chemically transform the PVA into a stable and analyte-selective matrix.
Other types of holographic recording material known to those skilled in the art are also unsuitable for a variety of reasons.
For example, when holograms made by the dichromating method are immersed in liquid, the voids fill up and the refractive index modulation is lost; hence these materials are entirely unsuitable for use as liquid phase chemical or biochemical sensors.
Photopolymer hologram

Method used

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  • Holographic sensors and their production
  • Holographic sensors and their production
  • Holographic sensors and their production

Examples

Experimental program
Comparison scheme
Effect test

example 1

An Amylase Sensor

Starch gratings have the potential to be used as biosensors to detect the concentration of the digestive enzyme alpha-amylase in a body fluid. This can be vitally important as an indication of acute pancreatitis. However starch does not lend itself to the production of ultra-fine grain photographic emulsion when using the conventional technique with gelatin, because it causes severe grain growth before the gelation occurs.

Five steps are described for preparing and using the sensor. These are:

1. The treatment of glass to take a starch coating.

2. The preparation and coating of a layer of starch.

3. The introduction of a light-sensitive fine grain silver halide deposit in the pre-coated starch layer by a diffusion process.

4. Exposure and development to record an optical hologram.

5. Use of the starch hologram as a sensor for amylase.

Step 1

Presubbing coating:

Solution A

The powdered carbohydrates are added to the cold water and stirred on a heater until the temperature reac...

example 2

An Ethanol Sensor

A microscope slide is presubbed as follows: a 1% solution of 3-(trimethoxysilyl)propyl methacrylate in dry acetone is poured over it and left overnight to evaporate and hydrolyse on the glass surface. Excess silane is removed by washing with acetone before drying.

A solution of polymerizable monomers is prepared as follows:

100 .mu.l of this solution is poured onto a subbed slide (laid horizontally) and covered with an inert sheet of non-stick as high density polythene of the type used for transfer lettering (Letraset). The sandwich is then exposed to UV light through the glass side until fully polymerised. After removing the polythene cover sheet, the sample is rinsed in methanol and dried in a warm air flow.

The sample is treated with silver nitrate as for Example 1, but this time it is necessary for the 0.25 M silver nitrate to be in 50% water / 50% 2-propanol to enable it to readily penetrate the polymer. The slide is left in contact with the solution for an hour (ev...

example 3

Na / K Sensors

Sensors capable of measuring the concentration of sodium ions in the presence of potassium ions and vice versa are made.

The liquid solution is poured over a presubbed microscope slide and the same treatment is carried out as in Example 2, to produce a grating which can be cut to suit a spectrometer cuvette or mounted at the end of a fibre optic cable. Thus the silver grating is embedded in a copolymer of methacryloyl 12 crown 4 and HEMA in the approximate mole ratio of 60:40. Since the grating is subjected to high concentrations of salt solutions during preparation, it first requires extensive rinsing in several changes of de-ionized water for at least an hour before it can be used as a sensor.

FIG. 3a is a graph of cation concentration ([+]; mM) against wavelength shift (d.sub..lambda. ; nm). It contrasts the effects of sodium ions (.circle-solid.) and potassium ions (.tangle-solidup.) on the response of the hologram.

By the same general procedure, but using the converse ...

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Abstract

A method for the production of a holographic sensor wherein the holographic recording material forming the sensitive element is a polymer matrix, which comprises diffusing into the matrix one or more soluble salts that undergo reaction in situ to form an insoluble sensitive precipitate; and recording a holographic image. This method allows the production of a holographic sensor wherein the holographic recording material forming the sensitive element is an insoluble polymer film.

Description

This invention relates to a chemical sensor based on a sensitive element which is a hologram made from a silver halide-based recording material.BACKGROUND TO THE INVENTIONMany different approaches to producing chemical sensors have been described in the academic and patent literature. There exists a wide range of different transduction mechanisms, which can be married with a suitable chemical or biochemical interface to realise a more or less selective sensor capable of identifying and / or quantitating a particular chemical substance. Transducers that have been successfully applied include those harnessing electrical, acoustic or optical phenomena.WO-A-9526499 discloses a new class of optical sensor, the holographic chemical sensor, based on a volume hologram. This configuration has the unique feature that the analyte-sensitive matrix film has the optical transducing structure disposed throughout its volume. Because of this physical arrangement of the transducer, the optical signal g...

Claims

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Application Information

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IPC IPC(8): G01N21/77G03H1/02
CPCG01N21/77G03H1/02G03H1/181Y10T436/11G03H2001/186G03H2260/16Y10T436/10G03H2001/0044
Inventor BLYTH, JEFFREYLOWE, CHRISTOPHER ROBINMAYES, ANDREW GEOFFREYMILLINGTON, ROGER BRADLEY
Owner SMART HOLOGRAMS
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